Modern vehicles typically include an on-board electronic system that manages, measures, and reports operation of the vehicle's various subsystems. These on-board electronic systems may include or otherwise support on-board diagnostic (OBD) services that enable vehicle owners and repair technicians to access diagnostic information or other forms of operational information from the vehicle. For example, an on-board electronic system of a vehicle may be accessed via a data interface in the form of a physical connector or port. OBD information may be communicated over this data interface using a variety of protocols, including ALDL, OBD-I, OBD-1.5, OBD-II, etc., to name a few examples.